The use of chemotherapy during pregnancy does not appear to affect the cognitive or heart-related health of the babies who are subsequently born, a new study indicates.

European researchers looked at children up to the age of 18 years, whose mothers had undergone chemotherapy while pregnant with them. The children were examined when they were born and again at the ages of 18 months, five to six year, eight to nine, 11 to 12, 15 to 16 and finally, 18 years.

Altogether, 68 mothers were involved and all had undergone chemotherapy for different types of cancer, including breast cancer, cervical cancer and leukaemia. Some of the women underwent chemotherapy on its own, while others had it in combination with radiotherapy, surgery or both.

According to the researchers, this marks the first time that children over the age of 18 months have been examined after their mothers underwent chemotherapy during pregnancy.

The children's cognitive health, such as intelligence, memory, attention and the ability to regulate behaviour, was examined, while their cardiac function was also assessed.

The researchers found that growth and general health and development were similar among the children when compared to their peers. Cognitive development was normal and no heart-related abnormalities were found.

However, the researchers did note that many of the children born after their mothers had undergone chemotherapy, were born prematurely and this did appear to have an effect on cognitive development.

"Our results so far suggest that children who were prenatally exposed to chemotherapy seem to do as well as children in the general population and that the treatment does not influence the development of mental processes or the functioning of the heart," commented lead researcher, Prof Frederic Amant, of the University Hospitals Leuven in Belgium.

However, he emphasised that it is important to ‘prevent pre-term birth and continue pregnancy until at least 37 weeks' as the findings suggest that children ‘suffer more from prematurity than from prenatal chemotherapy'.

"Pregnant women who are receiving chemotherapy often have delivery induced from the moment the foetus is viable although not mature. Our results suggest this should be avoided," Prof Amant said.

He explained that based on their findings, the researchers believe that pregnant women with cancer ‘do not need to delay their cancer treatment or terminate their pregnancy'.

However, he added that at this stage, ‘we do not know the full, long-term consequences of prenatal chemotherapy, including its effect on the children's fertility and likelihood of developing cancers when they are older'. As a result, studies in this area are set to continue.

Details of these findings were presented at the 2011 European Multidisciplinary Cancer Congress in Stockholm.